The present patent application claims the right of priority under 35 U.S.C. xc2xa7119 (a)-(d) and 35 U.S.C. xc2xa7365 of International Application No. PCT/EP99/01832, filed Mar. 19, 1999, which was published in German as International Patent Publication No. WO 99/52153 on Oct. 14, 1999, which is entitled to the right of priority of German Patent Application No. 198 14 653.1, filed Apr. 1, 1998.
The present invention relates to photovoltaic modules which contain one or more layers consisting of a multi-layer composite body, and relates to the use thereof for fixed or mobile power generation.
Glass is used almost exclusively as the covering for rigid photovoltaic modules. Coverings of glass are characterised by their poor mechanical loading capacity.
Coverings of transparent plastics are known instead of glass. These predominantly consist of polycarbonate plates. They are used when a higher mechanical loading capacity is required, as is the case on sailing boats for example. The modules are inserted in the deck superstructure here, so that the possibility of the modules being trodden on cannot be ruled out. Modules comprising polycarbonate as a covering have the disadvantage that they have a poor resistance to weathering. Moreover, they are permeable to water vapour, so that the photovoltaic modules can corrode. This results in these modules having to be replaced after short periods.
It is already known that sheets of fluoropolymer can be used as a transparent covering sheet in light, flexible photovoltaic modules. Both pure fluoropolymers, such as polyvinyl fluoride (PVF), and modified fluoropolymers, such as ethylene-tetrafluoroethylene copolymers (ETFE), are used here as sheets. Examples of sheets which are used for the aforementioned purpose include Tedlar(copyright) or Tefzel(copyright), which are both commercial products of the Du Pont company.
Three-layer sheets comprising a polyvinyl fluoride/polyester/polyvinyl fluoride layer structure are also used as backing sheets for photovoltaic modules. One example thereof is Icosolar(copyright), a commercial product of the Isovolta company.
Photovoltaic modules with coverings of fluoropolymer sheets only have a limited mechanical loading capacity. Fluoropolymer sheets exhibit poor printability.
The underlying object of the present invention is to provide photovoltaic modules having improved properties. The object is primarily to improve printability compared with photovoltaic modules having coverings of fluoropolymer. The object is also to improve the mechanical loading capacity. There should be a saving in weight and an increase in fracture-resistance compared with photovoltaic modules with glass coverings. The resistance to weathering, the impermeability to water vapour and the scratch-resistance should be improved compared with photovoltaic modules having polycarbonate as a covering. The low temperature-resistance of photovoltaic modules having a fluoropolymer as a covering should be increased.
This object according to the invention is achieved by photovoltaic modules which are characterised in that they contain one or more layers consisting of a multi-layer composite body, which contains at least one layer of polycarbonate and at least one layer of a fluorine-containing polymer.